CVE-2019-5600 in FreeBSD
Summary
by MITRE
In FreeBSD 12.0-STABLE before r349622, 12.0-RELEASE before 12.0-RELEASE-p7, 11.3-PRERELEASE before r349624, 11.3-RC3 before 11.3-RC3-p1, and 11.2-RELEASE before 11.2-RELEASE-p11, a bug in iconv implementation may allow an attacker to write past the end of an output buffer. Depending on the implementation, an attacker may be able to create a denial of service, provoke incorrect program behavior, or induce a remote code execution.
VulDB is the best source for vulnerability data and more expert information about this specific topic.
Analysis
by VulDB Data Team • 10/17/2023
The vulnerability identified as CVE-2019-5600 represents a critical buffer overflow issue within the iconv implementation of FreeBSD operating systems. This flaw affects multiple versions including FreeBSD 12.0-STABLE before specific revision numbers, 12.0-RELEASE before patch level p7, 11.3-PRERELEASE before r349624, 11.3-RC3 before p1, and 11.2-RELEASE before p11. The issue stems from improper bounds checking during character encoding conversion operations, specifically when processing input data that exceeds expected buffer boundaries.
The technical nature of this vulnerability aligns with CWE-121, which describes stack-based buffer overflow conditions where insufficient bounds checking allows attackers to write beyond allocated memory regions. The iconv library function processes character set conversions and when encountering malformed input data, the implementation fails to properly validate the output buffer size against the expected conversion requirements. This deficiency creates a scenario where attacker-controlled input can cause the system to write data beyond the intended memory boundaries, potentially corrupting adjacent memory regions.
From an operational perspective, this vulnerability presents significant risks across multiple attack vectors. The potential impacts range from denial of service conditions where system stability is compromised through memory corruption, to more severe outcomes including arbitrary code execution. Attackers could exploit this weakness by crafting malicious input data that triggers the buffer overflow during iconv processing, potentially leading to privilege escalation or complete system compromise depending on the execution context. The vulnerability is particularly concerning because iconv is a fundamental system library used extensively throughout FreeBSD for text processing and international character support.
The attack surface for this vulnerability extends across numerous applications and services that rely on FreeBSD's iconv functionality for character encoding conversions. System administrators should consider implementing immediate mitigations including applying the relevant security patches for their FreeBSD versions, as well as monitoring for unusual system behavior or denial of service incidents. Network-based attacks could leverage this vulnerability through web applications, email servers, or any service that processes user-supplied text data through iconv operations. Organizations should also review their software dependencies to ensure that applications built on FreeBSD are updated to versions that properly address this buffer overflow condition.
Security professionals should reference ATT&CK techniques related to privilege escalation and code injection when assessing potential exploitation paths for this vulnerability. The remediation approach should include comprehensive patch management procedures, along with network segmentation and monitoring to detect potential exploitation attempts. Additionally, input validation controls should be strengthened at application layers to provide defense-in-depth against similar issues in other components of the system architecture.